The present invention relates to a control apparatus and a control system and, more particularly, to a microcomputer, a data processor or a semiconductor integrated circuit device having a packaged timer for driving a motor, and a technique which is effective if applied to a control system for driving the motor by using it.
The microcomputer is made, as described on pp. 540 and 541 of "LSI Handbook" issued by OHM on Nov. 30, 1984, by forming around a central processing unit CPU and over one semiconductor substrate functional blocks including a program holding ROM (Read Only Memory), a data latching RAM (Random Access Memory) and input/output circuits such as a timer for inputting/outputting data.
This microcomputer may be used for controlling the drive of a motor. For example, a single-chip microcomputer which has a packaged timer for performing the PWM (Pulse Width Modulation) output suited for the so-called "inverter motor control" such as the motor control of an air conditioner or an AC induction servo-motor, is disclosed in "H8/3003 Hardware Manual" issued by HITACHI in March of 1993. The inverter motor is driven with a three-phase sinusoidal signal (U, V and W). The aforementioned single-chip microcomputer drives the aforementioned motor by generating the PWM output which is approximated by a carrier wave having a higher frequency than that of the sinusoidal wave.
The aforementioned timer outputs the three-phase PWM with two up/down counters and three compare registers. In the so-called "180-degree power supply system", the so-called "dead time" has to be interposed between upper and lower arms so as to prevent the short-circuit of the arms. The compare registers are individually equipped with buffer registers for transferring the data to the compare registers when the counters reach their lower limit value (or valley) or their upper limit value (or crest).